To solve this, we present a new technique that separates the dye signal from this natural background. Our approach uses computer-based curve fitting to isolate multiple dyes at once, even in water with high natural fluorescence. We tested it at three field sites in Florida and Minnesota, and it performed well even where standard dye sensors often fail. This method also works with large datasets from frequent water sampling, helping researchers build clearer, more accurate pictures of how groundwater flows in real-world environments.